Introduction
The sun, mother of all life
The sun is the most important presumption for life on earth. Nothing would be able to live in our world without the sun. No plants, no animals and no humans would have been developed without our nearest star. You can say that the sun is the engine for the evolution.
It isn’t strange that the sun has been worshipped, admired and used by people since the birth of mankind. Man has had big use of the sun in its development, from the ancient Greeks who were among the first to use the sun for heating of water to the modern solar cells of the present day.
The sun, creator of energy forms
The sun isn’t just the mother of all life, it also creates almost all of the other energy forms. Most of the energy forms are just indirect solar energy.
Waterpower exists because the sun makes the oceans to become steam so that the water can flow back as rivers, with enormous power. Wind power exists because different parts of the atmosphere absorb different amounts of solar heat and then comes into collision with each other. All biological fuels gets, as you know, their energy using photosynthesis and all fossil fuels like oil and coal are biological material that has been transformed to fossil fuels under certain circumstances. As a matter of fact, you could say that nearly all energy is solar energy. However, in this assignment we shall explain a little about solar energy that hasn’t been transformed.*A1, C5
Reason
We chose solar energy as our assignment because we believe that it’s still not fully exploited with an enormous potential. We wanted to examine the economical facts of solar energy, the enviromental circumstances and we wanted to know more about how it works.
Sunlight is theoretically an unbeatable way to heat houses, stores, offices and factories because of its security, its environmental aspects and that it’s probably going to be the least expensive way to gain energy.
The technology of solar electricity and solar heating is yet in its childhood but solar power will most likely be able to compete with the conventional processes to make electricity and heat as technology makes progress, especially as the sun won’t disappear as long as man exist, if nothing unpredicted happens. Compare that to traditional techniques based on fossil fuels and raw materials that will run out in the next few decades.
The disadvantage of solar electricity is that it is very expensive and that makes it impossible to build big foundations, but that will change as cheaper, more efficient inventions sees the sunlight of the day.
History
Already the people of the classical antiquity
Many of the people of the classical antiquity, for example Romans, Greeks, Babylonians, Egyptians and Aztecs used the sun in a, so to speak, commercial purpose. We have always used the sun but not with a great effort from our side, but already the inventorous Greeks began to use the sun “active”. The first building that used the sunrays was the gifted Socrates’ “sunhouse” which was built around year 400 BC. The builders have built the house so that it’s cool in the summer and warm in the winter with the greatest of efforts. They achieved this by placing walls, windows and other openings so that the position of the sun on the sky is used for the best.
They have also used big walls of stone surrounded by mirrors that let out the heat they gathered at day at night when the need is the biggest. These are techniques that are used in more developed forms even today in so called passive solar heating. Good work, Socrates.*A1
The dark medieval times with quite good showers
Much of the techniques that were used by the ancient Romans and Greeks were forgotten in the “dark” middle ages. Also the technology of sunlight was nowhere to be seen, even if some people used black-painted barrels to heat shower water. The heated water was tapped through a hole and then used for cleaning.*A1
The photovoltaic effect
In the year of 1839 was the Frenchman Edmond Becquerel experimenting with two conductive metalpieces in a semi-conductive fluid. What he discovered was that the conducting capacity of an object was increased when it was exposed to light. The light was transformed into electricity. This physical phenomenon was named “the photovoltaic effect”, shortened “the PV effect”.*A1, C1, C6
Edmond Becquerel was merely nineteen at his fantastic discovery and that’s probably one of the reasons that his observations were considered as very interesting but nothing that could be used practically.
In the year of 1873 an Englishman called Willoughby Smith continued the research of the photovoltaic effect when he was examining which materials that were fitted to build a new telegraph circuit to France. He then noticed that the element selenium was very light sensitive and therefor very susceptible for the PV effect. This first observation of the photovoltaic effect in an element made many scientists exalted over the new possibilities and they began to work with a new intensity.
The scientists discovered that so called semi-conductors, that’s materials that doesn’t conduct electricity as good as metals but yet not as bad as isolators, for example selenium, germanium and copperoxide, had the greatest capability for the task.*A1, C2
In the beginning of the 1880’s was the first, primitive solar cell-prototypes made by the Swiss Charles Fritz. He used the element selenium. Solar cells made of selenium never became a success and no industrial mass production was started as they were expensive and they had a bad efficiency rate at a half percent in turning light to electricity. That is, only half a percent of the energy bound to the sunlight was transformed into electricity.*A1, A9
Big progress thanks to silicon
Since Edison obtained the patent on the gas filled bulb in 1898 and the practical value of electricity was proved once and for all has the demand for electricity increased. In the beginning of electricity use were only turbines that was powered with the combustion of oil, wood and gas.*A1, C5, C6
In 1921 one of the greatest physicians of our time, Albert Einstein, won the Nobel Prize for his discoveru of the law behind the photovoltaic effect.*D1
The scientists once again made major progress in solar electricity in the 1930’s and the 1940’s, especially after World War Two, and the basics to the modern solar cells were made. In particular were giant steps taken in the end of the 40’s when scientist developed a method to make pure, crystalline silicon out of sand. The method was called the Czochralski method. With the silicon of the Czochralski was the American company Bell Laboratories able to make a new kind of solar cells that increased the efficiency rate at 4% to one at 12%. You can say that Bell Laboratories invented the technology that solar cells are built with even today.*C5, C1
In the 1950’s the scientists started to practise experiments with solar cells that would work practically. The tests didn’t turn out as good as they had hoped but it was enough to keep the major companies to continue their research. Research in this high technological level cost a lot of money and resources. Without the big companies would the technique of today not be at this level.*C5
Help from the space travel competition
In the 1950’s the hectic, explosion-like race in space travel technology between Sovjet and America. They were looking for a reliable, long-lasting energy source and solar energy fit like a glove.
In the year of 1950 the satellite of the US Vanguards used small amounts of solar cells to run their radio and other minor devices. These solar cells worked so well that the space scientists continued to work with solar energy. Much of the technology of solar cells is the work of space technicians and almost all of the satellites are powered by solar energy today.*A10, C5
The interest for solar cells increased dramatically during the 1970’s when it was proved that the fossil fuels were exhaustable once and for all with a following oil crisis in the Middle East and in America as a result.
The scientists then increased their efforts to develop an efficient, cheap and reliable type of solar cells. During the 80’s was much of the technology that the present days solar cells chose of material and design relies on developed.*A6, A1, C5
Today
Solar heating is greatly used today, especially in newly built and newly restored houses an dit’s a well working complement to more traditional heating sources like oil, coal and biofuel. For example, in 1992 was 83 % of the houses built with solar panels supposed to warm water and in 1993 was four and a half million buildings in Japan equipped with solar heatingsystems with the same purpose.*A2, A3
Solar electricity is yet not an energy source to count with. Photovoltaic cells are only efficient in consumer products like mini calculators, lamps, clocks, radio devices and for places far away from electric mains where it would be more expensive to connect to the power lines than to install solar cell systems.
The development goes forward with an alarming speed and in a relatively near future will solar electricity probably be visible on diagrams over electricity sources which the solar electricity isn’t able to today.*C5
Enviromental aspects
From an enviromental point of view one can say that solar energy is one of the most non-pollutive and best ways to gain electricity. There is no combustion, it’s safe, the raw material is everywhere, it’s free and it won’t run out during the existence of man. The only risks exist in the making of solar energy devices.
No combustion
There is really no combustion or other pollutions when you work with finished solar power equipment. No greenhouse gases, no damage to the ozon layer and no heavy metals in the nature.
If we’re ever going to be able to tackle the greenhouse effect, we have to start taing the alternative energy forms seriously. Especially as the undevelopt countries are gathering force to their industrial revolution in this very moment. This will bring an enormous pressure on the environment. Especially India and China are thanks to their great populations a ticking environmental bomb.
We who live in the northern half of the world are today responsible for a majority of the pollution in spite of the fact that we are much less people than the people of the southern hemisphere.
We who live in Western Europe, North America, Australia, New Zeeland, Hong Kong, Japan, Singapore and the oil producing countries in the Middle East provide for about twentyfive per cent of the total population of the world and we consume sixtyfive per cent of the world's resources. Is it really possible for us to tell these people that they can't have the same arrogant, wasting lifestyle as we have. Shouldn't we make a good example and reduce our pollution by using alternative energy sources and restrictions of the industry?
Infinite, free and exists everywhere
The sun as raw material is unbeatable. Every day it sends rays with an amazing power, about 1 kW/m2. Thats about 9000 times more than we consume on a day. As long as man lives will it be there, sending its radiation to Earth. Coal, oil, gas and uranium will run out the nearest decade if we continue and even increase our intensive energy use.
The sun itself costs nothing as a raw material. The prices on fossil fuels will rise the more we consume and this will be an advantage for the solar energy. A society where we use the sun completely free of charge for all energy demanding work doesn't seem like an impossible utopia.
The solar energy exists in incredible amounts everywhere, even here in Sweden. As a matter of fact, we have as many hours when the sun shines in the sumer here as they do in Northern Africa. Over the whole year is it of course less.
We don't need to import the raw material from far away places and in that way pollute the environment with foul transport. Oil tankers that destroy entire ecological systems by running aground and dangerous lorrys that are fully loaded with noxious and explosive gases will be no more than memories. Besides, the cost for energy will sink when we don't have to pay for this insane transport.
A safe energy source
Solar energy is an energy source without risks. Nuclear power, which was believed to be the only energy source we would need in the future when it was first developed, has turned out to be extremely hazardous. Tjernobyl and Harrisburg made us realize which dangers nuclear power brings and the people in Sweden have decided to liquidate the nuclear power. If that happens will solar power, with the right help from authorities in the shape of subventions and contributions, be a great help.
Counteracts the greenhouse effect
Solar energy actually helps to lower the speed of the greenhouse effect - even if it's really little. That you temporary store solar energy reduces the amount of heat in the atmosphere.
Recyclable
All the ingredients in a solar cell, with some exceptions, can be recycled. Nearly none of the materials has been classified as toxic or dangerous in any way.
Disadvantages
There are disadvantages environmentally with solar energy, especially at the making of solar devices. A lot of scientists has done so called life cycle analysises on solar cells and solar panels to see how they affect the environment during certain parts of their existence.
It has been verified that the aluminium in the solar heating devices through the production leads to pressure on the environment. Aluminium demands great amounts of energy to be extracted out of bauxit. The manufacturers choose this material because it's a lot better in gathering heat than a copperabsorbator in a sunpanel, they regain the loss.
Among the solar cells is it the otherwise so promising cells with thin layers that are a problem. Usual silicon cells are made of common materials and without hazardous liquids. In the cells with thin layers however, there are rare materials, as indium, poisonous metals, as cadmium and toxic or explosive gases, as hydroselenid.
If it will be possible to build large scale power plants in the future, they should be built in desert like the Sahara- or the Gobidesert because of the intensity of the sun. This will take relatively big areas of the desert and despite that there aren't many animals or plants there, the ones that do live there will be affected and maybe even harmed by the power plant. But if you compare this to, for example, water power, you’ll see that it is fractions of the area per kWh that is needed.*A6, A7, A10, C2, C4, C5, C6, D2
Economy
The development of the solar energy has made progress with great velocity – and will keep on doing that. The efficiency rate has risen and the prices have gone down much the latest thirty years, but the prices are still too high to really compete with fossil fuels and nuclear power. The prices would have to sink at least ten times to really be in the contest. Still, the solar power can already be a good choice in places far away from power lines where it would be more expensive to connect than to install solar energy systems.
Today, the manufacturing of solar cells and solar panels is still a small business. Thus, the factories have been able to use silicon from the waste of the microchip industry and they have been able to mine rare materials as indium without a measurable affect on nature.
If we’re supposed to start a large scale production, we have to find better sources of raw material. New methods to gain the raw material is then a presumption to be able to get the prices down to an acceptable level.
A lot of scientists predict that the prices on solar energy will sink at the same time that the exhaustable energyforms will be more expensive. They think that in a near future, five to thirty years, will the solar energy be less expensive than conventional energyforms.